title: Acid sensitive background potassium channels K2P3.1 and K2P9.1 undergo rapid dynamin-dependent endocytosis.
abstract: Acid-sensitive, two-pore domain potassium channels, K(2P)3.1 and K(2P)9.1, are implicated in cardiac and nervous tissue responses to hormones, neurotransmitters and drugs. K(2P)3.1 and K(2P)9.1 leak potassium from the cell at rest and directly impact membrane potential. Hence altering channel number on the cell surface drives changes in cellular electrical properties. The rate of K(2P)3.1 and K(2P)9.1 delivery to and recovery from the plasma membrane determines both channel number at the cell surface and potassium leak from cells. This study examines the endocytosis of K(2P)3.1 and K(2P)9.1. Plasma membrane biotinylation was used to follow the fate of internalized GFP-tagged rat K(2P)3.1 and K(2P)9.1 transiently expressed in HeLa cells. Confocal fluorescence images were analyzed using Imaris software, which revealed that both channels are endocytosed by a dynamin-dependent mechanism and over the course of 60 min, move progressively toward the nucleus. Endogenous endocytosis of human K(2P)3.1 and K(2P)9.1 was examined in the lung carcinoma cell line, A549. Endogenous channels are endocytosed over a similar time-scale to the channels expressed transiently in HeLa cells. These findings both validate the use of recombinant systems and identify an endogenous model system in which K(2P)3.1 and K(2P)9.1 trafficking can be further studied.
authors.affiliation: Human Development and Health; Centre for Human Development, Stem Cells and Regeneration; Faculty of Medicine; University of Southampton; Southampton, UK.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mant
authors.forename: Sarah
authors.initials: S
authors.lastname: Williams
authors.forename: Ita
authors.initials: I
authors.lastname: O'Kelly
mesh_terms: D000818:Animals; D034281:Dynamins / Q000378:metabolism*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D009419:Nerve Tissue Proteins; D024683:Potassium Channels, Tandem Pore Domain / Q000378:metabolism*; D051381:Rats
chemical_list: C407082:Kcnk9 protein, rat; D009419:Nerve Tissue Proteins; D024683:Potassium Channels, Tandem Pore Domain; C420132:potassium channel subfamily K member 3; D034281:Dynamins
keywords: Imaris; K2P channel; TASK; caveolin; clathrin; dynamin; endocytosis; potassium channel; recycling